竹内謙善 (タケウチ ケンゼン)
創造工学部 創造工学科 創発科学研究科 創発科学専攻 | ![]() | ||
Dynamic FEM analysis is valid for designing rotating machinery to reduce its vibration problem when we may ensure enough accuracy of the analysis. Surrogate multiple objective optimization method is one of the most effective methods for structural identification improving the FEM analysis model of a structure to adjust the natural frequency analysis results to the experimental results. In this study the structural identification method is applied to coil mounted stator core of an induction motor to determine the Young's modulus of the principal components on the FE model minimizing the analysis errors of the natural frequencies of the 2-lobe and 3-lobe circular modes to the corresponding experimental results. The accurate FE model of the end-windings is obtained by this method.
There are various methods for estimating the vibration characteristics. One of the reasons for this is the need to reduce noise and vibration in industrial electrical equipment from the viewpoint of environmental loading. We focus on transformers as one of the equipment. In transformers, coils and iron cores stretch by magnetostriction and generate noise on the boundaries of them. Precise estimation of the vibration characteristics of transformers using finite element method is important to reduce the noise. However, the specification of material constants of iron cores is very difficult because cores consist of laminated thin steel plates. The slippage between plates affects macroscopic material constants. In this paper, the Newton method based on the Adjoint variable method is applied to obtain the experimental values of eigenfrequencies, which are the characteristics of vibration. In addition, the identification of material constants is verified so that the error between the experimental and the measured values is zero.
This paper presents a formulation to identify the muscle activities from shape variation of organs in a swallow motion. Using a tongue model consisting of hyper elastic body and multi-muscle fibers, we consider that the shape variation is realized by the compulsory displacement on the boundary, and that muscle activities are assumed as initial stresses generated in the directions of the muscle fibers. The identification problem of the muscle activities is formulated using the magnitudes of the initial stresses as the design variables and the L2 squared norm of the reaction force on the boundary by the compulsory displacement as the cost function of minimization. Solution of the problem is presented based on the scheme using the H1 gradient method for topology optimization problem of density type. A numerical example using a previously developed data is introduced to show the effectiveness of the present approach.
This paper presents a formulation and solution of an identification problem of the muscle activities in an organ when a deformation of the organ was observed on boundary. This study is motivated by a medical interest of wishing to know the mechanism of swallow motion and cause of aspiration. In order to elucidate the mechanism, it is necessary to identify the contraction movement of the muscles. In this study, we assume that an organ consists of hyper elastic body, and the contraction movement is a finite deformation due to the generation of the anisotropic and inelastic strain. The strain is modeled as a function of a design variable which controls the contraction rate. Based on the assumption, we formulate a state determination problem of hyper elastic deformation by the compulsory displacement on the observed boundary using a given data. Using its solution, we define an objective function by the integral of the squared norm of the reaction force over the observed boundary, and construct an optimization problem seeking the design variable that minimize the objective function. Solution of the problem is presented as an iterative scheme using the H1 gradient method for topology optimization problem of density type. Numerical examples for a cubic and cylinder bodies demonstrste that the deformations are reproduced by the identified design variables.